WANTED: Furnished WG Zimmer for Summer (Frankfurt)

I am having an incredibly difficult time finding somewhere to live and any suggestions or info you could give me would be much appreciated! I have an internship this summer and I will be needing a room somewhere in North Frankfurt. I am a 19 year old college student and need the room between May 19 and August 15. I would prefer to live with girls around my own age or possibly even a family at a price I can pay with what I earn from my internship.